2B.3 Osmosis

• what is osmosis?

  the net movement of water molecules from an area of high water potential to lower passively across an partially permeable membrane.
• what is water potential?

  the tendency of water to move out of a solution.
• if a solution is dilute does it have high or low water potential?

  high.
• if a solution is concentrated does it have a high or low water potential?

  low.
• what is the water potential for pure water?

  0kPa.
• what happens in a hypertonic solution?

  water moves out of the cell as WPT inside is higher (less concentrated). this causes the cell to lose volume and contract (plasmolysis).
• what happens in a hypotonic solution?

  water moves into the cell as WPT is higher outside (more concentrated) this causes the cell to expand and bust (cytolysis).
• as concentration increases, what happens to water potential?

  it decreases.
• what is an isotonic solution?

  no net movement of water as WPT is equal inside and outside the call.
• name three factors that affect the rate of osmosis.

  • the gradient of WPT (the higher the quicker).• the thickness of the exchange surface (the thinner the quicker).• the surface area of the exchange surface (the larger the quicker).
• will a hypertonic solution be very negative or slightly negative?

  very negative.
• will a hypotonic solution be very negative or slightly negative?

  slightly negative.
• What happens if you put an animal cell in pure water?

  swells and bursts